Middleware is computer software that provides services to software applications beyond those available from the operating system. Middleware makes it easier for software developers to perform communication and input/output, so that programmers can focus on the specific purpose of their application. Middleware is the software that connects software components or enterprise applications. Middleware is the software layer that lies between the operating system and the applications on each side of a distributed computer network.
In computer programming, an application programming interface (API) is a set of routines, protocols, and tools for building software applications. An API expresses a software component in terms of operations, inputs, outputs and underlying types. An API defines functionalities that are independent of their respective implementations, which allows definitions and implementations to vary without compromising the interface.
A programming paradigm is a fundamental style of computer programming, serving as a way of building the structure and elements of computer programs. Capabilities and styles of various programming languages are defined by their supported programming paradigms. For instance, some programming languages are designed to follow only one paradigm, while others support multiple paradigms.